This invention relates to the field of geophysical prospecting and, more particularly, to a method for processing seismic data
Systematic contamination of seismic data stemming, for instance from sub-optimal acquisition efforts, can manifest itself as signal amplitude variations and as residual noise amplitude variations. Both forms of contamination are laterally correlated to their origin, most commonly the acquisition geometry. For cases where the shooting geometry causes the artifacts, they are referred to as acquisition footprints or imprints. Present algorithms use various techniques to reduce acquisition footprints. An approach disclosed in Morse, P. F. and Hildebrandt, G. F. (1989) Ground-roll suppression by the stack array, Geophysics, 54, No. 3, pp. 290-301, addresses the signal variation problem through correcting amplitudes, for instance by creating a uniform stack operator in seismic processing. However, as pointed out by Hampson, 1994, Relationship between wave-field sampling and coherent noise attenuation, 56th Annual Meeting of European Association of Geoscientists and Engineers, Abstracts Book, paper H054, array forming during processing can reduce the resolution and it is therefore better to acquire the data in an adequate fashion, but this increases the acquisition costs. A solution of Ronen, 1994, Handling irregular geometry: Equalized DMO and beyond, Society of Exploration Geophysicists 64th Annual Meeting Expanded Abstracts, pp. 1545-1548, makes use of a special DMO algorithm to even out amplitude variations.
The approach of Meunier, J. and Belissent, M., 1992 Reduction of 3D geometry-generated artifacts, 6th Venezuelan Geophysical Congress Abstracts, pp. 388-394, relies on the periodicity of the contamination. The algorithms in this group operate in a more suitable domain such as the wave-number (K) domain or most commonly the frequency-wave-number (FK) domain, for example. Necati Gulunay, Acquisition geometry footprints removal, Society of Exploration Geophysicists 69th Annual Meeting Expanded Abstracts, pp. 637-640. However, algorithms operating in the FK domain have the drawback that imprint removal only works effectively on events that have a single and constant orientation or dip.
A method for processing seismic data for removing distortion from seismic data comprising applying a unitary transform to a decomposed transform component of seismic data to obtain an modified transform component. The modified transform component is filtered and the filtered data are inverted to obtain time distance (T-X) or depth distance (Z-X) seismic data